1. Field of the Invention
This invention relates to leak testing of containers, and is particularly, but not exclusively, concerned with the leak testing of blow molded containers.
2. Description of the Related Art
It is an inherent feature of the blow molding process used for producing plastics bottles and the like that small holes are sometimes formed in the container walls due to the occurrence of flaws in the molding medium. It is therefore essential, in applications in which the container is required to be fluid tight, that each container is subjected to leak testing prior to use. Conventionally such leak testing is performed on a conveyor line by initially pressurising each container with air and subsequently detecting by means of a pressure transducer any decay of the pressure within the container which might indicate the occurrence of a leak. While this leak method operates satisfactorily in practice, it requires use of a pressure transducer which is both costly and delicate. Also, since the method requires monitoring of the pressure within the container over a period of a few seconds, the period of each testing cycle cannot be decreased below a certain value.